As Serena Williams began to fall behind in what would become her earliest Wimbledon exit in nearly a decade, her coach could tell something was awry.

Not the so-so serving. Or the bad backhands. This was a larger problem. "Right now, she doesn't have her usual ability to respond and turn matches around," said Patrick Mouratoglou, who has worked with Williams since 2012. "It was obvious when she trailed 3-0 in the second set. Nothing happened."

Unable to get back on track once she no longer had control of the match, five-time Wimbledon champion Williams lost to 25th-seeded Alize Cornet of France 1-6, 6-3, 6-4 on Saturday in the third round, the latest in a recent series of surprising Grand Slam busts.

"If I'm not playing a great, great match, these girls, when they play me, they play as if they're on the ATP Tour," Williams said, rolling her eyes.

She hadn't left Wimbledon so soon since 2005, also beaten in the third round. The No. 1-ranked and top-seeded Williams owns 17 Grand Slam titles, one fewer than Martina Navratilova and Chris Evert, but has departed before the quarterfinals at four of the past five majors. There were fourth-round losses at Wimbledon last year and the Australian Open in January, and a second-round loss at the French Open in May.

"It might be a bit premature to talk about her decline, but when she plays someone who finds the right tactics, she looks a bit lost on the court," Cornet said. "In my opinion, there are more and more players understanding how to play her."

Cornet also beat the 32-year-old American at the Dubai Championships in February, and watched video clips of that triumph before playing Saturday. "I just knew that I could do it, because I did it once," Cornet said.

Still, this result was rather unexpected, given that Cornet never had been past the third round at Wimbledon, and only once before reached a major's fourth round.

Saturday's match was halted in the third game because of showers. When they returned about 4 1/2 hours later - "the rain delay killed me a little bit," Cornet said - Williams was terrific, reeling off five games to grab the first set.

Then everything changed, because Williams couldn't find the mark. She finished with 29 unforced errors, 11 more than Cornet. Two particular strokes let Williams down: her serve, with seven double-faults and five breaks, and her backhand, with 12 unforced errors.

"I don't really know what I did wrong," said a blank-faced Williams. "Usually I do. Usually I know I did this, this and that."

It was by far the most significant outcome on a day full of starts and stops.